Throughout the world and particularly in the western United States there are regions in which seasonal water runoff is lost to storage because pipelines to transport the water flows to storage areas have only limited carrying capacity. The carrying capacity of a pipe depends on the diameter of the pipe, friction within the pipe, and other factors. The flow resistance of a pipe increases rapidly when the flow rate increases above onset of turbulent flow. During periods of moderate flow, the pipelines can transport the available water. During periods of heavy flow, however, pipelines cannot carry all of the water available. In addition, turbulence induced friction losses can consume significant unnecessary energy costs annually.
Since the early 1970's it has been know that certain materials when added to fluids in turbulent flow can substantially reduce friction. This friction reduction results in substantial increases in the capacity of the pipe (typically 30%) and reduction in the energy required to transport the fluid. There are a variety of suitable materials available, including polyacrylamides (either nonionic or partially anionic), polyoxyethylene glycol, xanthans, guar, carrageenan, and oil-soluble polymers.
At present such materials are expensive and therefore limited to the transport of valuable fluids such as oil, for example the Trans-Alaska Pipeline. Known materials cannot be added to water supplies, not only for cost reasons but also because such materials would make water unfit for consumption.
One method known for reducing turbulent flow on a surface that is in contact with a flowing fluid is to create small ridges or riblets on the surface. See K. N. Liu et al., "Drag reduction in pipes lined riblets," AATA Journal 28, 1697-8 (Oct. 1990). These discussions are very different from the present invention. In addition, some preliminary work has been done injecting long-chain polymer molecules into riblet grooves on a boat hull, generally aligned with the direction of travel of the boat. "Polymers and Riblets Reduce Hydrodynamic Skin Friction," Nasa Tech Briefs, 77-78 (Oct. 1991).